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The objective of this study was to determine the effect of the presence of recombinant ovine growth hormone either alone or together with follicle stimulating hormone (FSH) during ovine oocyte in vitro maturation (IVM) on nuclear maturation and subsequent embryo development. Moreover, the effect of growth hormine (GH) on embryo development whether influenced by the presence of foetal bovine serum (FBS) was assessed. The abattoir-derived oocytes were randomly divided into four treatment groups and cultured in maturation medium supplemented with: (i) 0.05 IU/ml FSH; (ii) 300 ng/ml roGH; (iii) FSH + roGH; and (iv) no FSH and GH (control). The percentages of germinal vesicle-stage oocytes in GH-treated group after 8 h of culture was significantly higher than the FSH and FSH + GH groups and lower than control (22.4%, 8.7%, 9.1%, and 32% respectively). The percentage of MII-stage oocytes was significantly increased in the presence of GH after 16 and 24 h of culture compared to the control (44.7% and 83.1% vs 32.6% and 73.6% respectively). There was no significant synergism between GH and FSH in terms of nuclear maturation. The blastocyst rates in serum-supplemented groups were enhanced by the presence of FSH and GH compared to the control (35.4% and 31.3 vs 11.4% respectively). Compared with either GH or FSH alone, the subsequent embryo development (blastocyst rate), however, was negatively influenced by co-presence of both hormones (22.8%). In contrast, the corresponding values were not affected in the absence of serum. In conclusion, GH had positive effect on nuclear maturation of sheep oocytes. Moreover, the pattern of the effect of GH on embryo development was influenced by the presence of FBS during IVM.

The objective of this study was to determine the effects of various methods of sperm pre-treatment on male pronuclear (MPN) formation and subsequent development of ovine embryos derived from in vitro-matured oocytes and intracytoplasmic sperm injection (ICSI). The effect of treatment of injected oocytes with dithiothreitol (DTT) on embryo development was also assessed. In Exp. 1, the injected oocytes with non-treated sperm were activated with three different procedures. The cleavage and blastocyst rates in those activated with DTT was lower (p<0.05) than those activated with either ionomycin (Io) +6-dimethylaminopurine (6-DMAP) or DTT + I + 6-DMAP. In Exp. 2, the effects of sperm pre-incubated with DTT, sodium dodecyl sulphate (SDS) or DTT + SDS as well as two-time frozen/thawed sperm (without cryoprotectant) on MPN formation and oocyte activation were examined. The non-treated sperm served as controls. The MPN formation in DTT + SDS group was higher (p<0.05) than other groups except for freeze-thaw group. No difference in the rate of activated ICSI oocytes was observed among groups. In Exp. 3, the effect of pre-treatment of sperm on subsequent development of ICSI embryos and blastocyst cell numbers were examined. The rates of cleavage and blastocyst formation as well as the blastocyst cell numbers were similar among the pre-treated and control groups. In conclusion, pre-treatment of sperm with DTT + SDS positively affected MPN formation, although the subsequent development capacity of the resulting embryos remained limited. Moreover, DTT was not effective on oocyte activation compared with Io + 6-DMAP after ICSI.

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Contents Despite the numerous potential applications of oocyte cryopreservation, the poor success rate has limited its practical applications. In livestock, particularly in ovine, the oocytes have low developmental competence following vitrification/warming process. Considering the occurrence of osmotic and oxidative stresses during the vitrification/warming process, the application of antioxidants and osmolytes may improve the developmental competence of vitrified/warmed oocytes. In the present study, we aimed to evaluate the effects of the addition of ascorbic acid (AA) and N‐acetyl cysteine (NAC) as antioxidants and glycine as an organic osmolyte either to the vitrification/warming solutions (VWS) or to the IVM medium on the developmental competence of vitrified/warmed ovine germinal vesicle stage oocytes. The survival rate in the vitrified groups was significantly lower than fresh ones. In vitrified/warmed oocytes, there was no significant difference in survival rate between supplemented and non‐supplemented groups. The addition of AA and/or NAC to the VWS or IVM medium and adding glycine to the IVM medium reduced the proportion of apoptotic oocytes and fragmented embryos, which was reflected as an increase in the proportions of metaphase II stage oocytes and blastocyst production. The best result was achieved by supplementing the IVM medium with NAC. In our study condition, antioxidants and glycine could improve the developmental competence of vitrified/warmed ovine immature oocytes, especially when added during IVM.

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Nuclear reprogramming of a differentiated cell in somatic cell nuclear transfer (SCNT) is a major concern in cloning procedures. Indeed, the nucleus of the donor cell often fails to express the genes which are a prerequisite for normal early embryo development. This study was aimed to evaluate the developmental competence and the expression pattern of some reprogramming related genes in bovine cloned embryos reconstructed with amniotic membrane stem cells (AMSCs) in comparison with those reconstructed with mesenchymal stem cells (MSCs) and adult fibroblasts (AF) as well as with in vitro fertilized (IVF) oocytes. In vitro matured abattoir-derived oocytes were considered as recipients and a hand-made cloning technique was employed for oocyte enucleation and nuclear transfer (NT) procedures. The expression pattern of genes involved in self-renewal and pluripotency (POU5F1, SOX2, NANOG), imprinting (IGF2, IGF2R), DNA methylation (DNMT1, DNMT3A), histone deacetylation (HDAC2), and apoptosis (BAX, BCL2) were evaluated in NT and IVF derived embryos. Despite the insignificant difference in cleavage rate between reconstructed and IVF oocytes, the blastocyst rate in the IVF group was higher than that of other groups. Among reconstructed oocytes, a higher blastocysts rate was observed in MSC-NT and AMSCs-NT derived embryos that were significantly higher than AF-NT derived ones. There were more similarities in the expression pattern of pluripotency and epigenetic modification genes between MSC-NT and IVF derived blastocysts compared with other groups. In conclusion, considering developmental competence, AMSCs, as alternative donors in SCNT procedure, like MSCs, were prone to have more advantage compared with AF.

The aim of the present study was to examine the effects of fetal bovine serum (FBS) concentration, equilibration time, and oocyte pre-treatment with cytochalasin B (CCB) on subsequent development of vitrified-warmed ovine immature (GVCOCs) and matured (MII) oocytes with (MIICOCs) or without cumulus cells (MIIDOs). In Experiment 1, the effects of FBS concentrations (10 and 20%) during the vitrification-warming procedure were examined. Survival rates after warming were not different between GVCOCs, MIICOCs and MIIDOs oocytes. After in vitro fertilization, rate of cleaved embryos in MIICOCs group at the presence of 20%FBS was higher than MIIDOs and GVCOCs groups. In Experiment 2, the effects of equilibration times (5, 7, and 10 min) were examined. There was no difference in survival rate of vitrified-warmed oocytes equilibrated at different times. Although, the rate of cleavage in MIICOCs and MIIDOs oocytes equilibrated for 10 and 7 min, respectively, was higher than 5 min equilibrated MIIDOs and 7 and 10 min equilibrated GVCOCs oocytes. In Experiment 3, the effects of oocyte pre-treatment with CCB were examined. Despite the insignificant difference in survival rate of vitrified-warmed ovine immature and matured oocytes, the rates of cleavage in CCB pretreated groups were significantly lower than untreated groups. Moreover, the blastocysts were only derived from those cumulus enclosed vitrified-warmed germinal vesicle (GV) and MII oocytes that had been exposed to 10% FBS in the absence of CCB. In conclusion, the presence of cumulus cells, 10% FBS, and the omission of CCB were beneficial for post-warming development of vitrified ovine oocytes.